diff options
| -rw-r--r-- | doc/demuxers.texi | 9 | ||||
| -rw-r--r-- | libavformat/isom.h | 1 | ||||
| -rw-r--r-- | libavformat/mov.c | 55 |
3 files changed, 40 insertions, 25 deletions
diff --git a/doc/demuxers.texi b/doc/demuxers.texi index b474a24278..26ae768d7a 100644 --- a/doc/demuxers.texi +++ b/doc/demuxers.texi @@ -726,6 +726,15 @@ specify. @item decryption_key 16-byte key, in hex, to decrypt files encrypted using ISO Common Encryption (CENC/AES-128 CTR; ISO/IEC 23001-7). + +@item max_stts_delta +Very high sample deltas written in a trak's stts box may occasionally be intended but usually they are written in +error or used to store a negative value for dts correction when treated as signed 32-bit integers. This option lets +the user set an upper limit, beyond which the delta is clamped to 1. Values greater than the limit if negative when +cast to int32 are used to adjust onward dts. + +Unit is the track time scale. Range is 0 to UINT_MAX. Default is @code{UINT_MAX - 48000*10} which allows upto +a 10 second dts correction for 48 kHz audio streams while accommodating 99.9% of @code{uint32} range. @end table @subsection Audible AAX diff --git a/libavformat/isom.h b/libavformat/isom.h index ef8f19b18c..625dea8421 100644 --- a/libavformat/isom.h +++ b/libavformat/isom.h @@ -305,6 +305,7 @@ typedef struct MOVContext { int32_t movie_display_matrix[3][3]; ///< display matrix from mvhd int have_read_mfra_size; uint32_t mfra_size; + uint32_t max_stts_delta; } MOVContext; int ff_mp4_read_descr_len(AVIOContext *pb); diff --git a/libavformat/mov.c b/libavformat/mov.c index 2aed6e80ef..351ecde770 100644 --- a/libavformat/mov.c +++ b/libavformat/mov.c @@ -2925,6 +2925,8 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom) unsigned int i, entries, alloc_size = 0; int64_t duration = 0; int64_t total_sample_count = 0; + int64_t current_dts = 0; + int64_t corrected_dts = 0; if (c->fc->nb_streams < 1) return 0; @@ -2965,11 +2967,34 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom) sc->stts_data[i].count= sample_count; sc->stts_data[i].duration= sample_duration; - av_log(c->fc, AV_LOG_TRACE, "sample_count=%d, sample_duration=%d\n", + av_log(c->fc, AV_LOG_TRACE, "sample_count=%u, sample_duration=%u\n", sample_count, sample_duration); - duration+=(int64_t)sample_duration*(uint64_t)sample_count; - total_sample_count+=sample_count; + /* STTS sample offsets are uint32 but some files store it as int32 + * with negative values used to correct DTS delays. + There may be abnormally large values as well. */ + if (sample_duration > c->max_stts_delta) { + // assume high delta is a correction if negative when cast as int32 + int32_t delta_magnitude = (int32_t)sample_duration; + av_log(c->fc, AV_LOG_WARNING, "Too large sample offset %u in stts entry %u with count %u in st:%d. Clipping to 1.\n", + sample_duration, i, sample_count, st->index); + sc->stts_data[i].duration = 1; + corrected_dts += (delta_magnitude < 0 ? (int64_t)delta_magnitude : 1) * sample_count; + } else { + corrected_dts += sample_duration * sample_count; + } + + current_dts += sc->stts_data[i].duration * sample_count; + + if (current_dts > corrected_dts) { + int64_t drift = (current_dts - corrected_dts)/FFMAX(sample_count, 1); + uint32_t correction = (sc->stts_data[i].duration > drift) ? drift : sc->stts_data[i].duration - 1; + current_dts -= correction * sample_count; + sc->stts_data[i].duration -= correction; + } + + duration+=(int64_t)sc->stts_data[i].duration*(uint64_t)sc->stts_data[i].count; + total_sample_count+=sc->stts_data[i].count; } sc->stts_count = i; @@ -3856,13 +3881,10 @@ static void mov_build_index(MOVContext *mov, AVStream *st) unsigned int distance = 0; unsigned int rap_group_index = 0; unsigned int rap_group_sample = 0; - int64_t last_dts = 0; - int64_t dts_correction = 0; int rap_group_present = sc->rap_group_count && sc->rap_group; int key_off = (sc->keyframe_count && sc->keyframes[0] > 0) || (sc->stps_count && sc->stps_data[0] > 0); current_dts -= sc->dts_shift; - last_dts = current_dts; if (!sc->sample_count || sti->nb_index_entries) return; @@ -3973,26 +3995,8 @@ static void mov_build_index(MOVContext *mov, AVStream *st) current_offset += sample_size; stream_size += sample_size; - /* A negative sample duration is invalid based on the spec, - * but some samples need it to correct the DTS. */ - if (sc->stts_data[stts_index].duration < 0) { - av_log(mov->fc, AV_LOG_WARNING, - "Invalid SampleDelta %d in STTS, at %d st:%d\n", - sc->stts_data[stts_index].duration, stts_index, - st->index); - dts_correction += sc->stts_data[stts_index].duration - 1; - sc->stts_data[stts_index].duration = 1; - } current_dts += sc->stts_data[stts_index].duration; - if (!dts_correction || current_dts + dts_correction > last_dts) { - current_dts += dts_correction; - dts_correction = 0; - } else { - /* Avoid creating non-monotonous DTS */ - dts_correction += current_dts - last_dts - 1; - current_dts = last_dts + 1; - } - last_dts = current_dts; + distance++; stts_sample++; current_sample++; @@ -8577,6 +8581,7 @@ static const AVOption mov_options[] = { { "decryption_key", "The media decryption key (hex)", OFFSET(decryption_key), AV_OPT_TYPE_BINARY, .flags = AV_OPT_FLAG_DECODING_PARAM }, { "enable_drefs", "Enable external track support.", OFFSET(enable_drefs), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, FLAGS }, + { "max_stts_delta", "treat offsets above this value as invalid", OFFSET(max_stts_delta), AV_OPT_TYPE_INT, {.i64 = UINT_MAX-48000*10 }, 0, UINT_MAX, .flags = AV_OPT_FLAG_DECODING_PARAM }, { NULL }, }; |